In our work, the removal of cationic and anionic dyes from water was estimated both experimentally and computationally. We check the selectivity of the adsorbent, Zn–Fe layered double hydroxide (LDH) toward three dyes. The physical and chemical properties of the synthesis adsorbent before and after the adsorption process were investigated using X-ray photoelectron spectroscopy, energy dispersive X-ray, X-ray diffraction, FT-IR, HRTEM, and FESEM analysis, particle size, zeta potential, optical and electric properties were estimated. The effect of pH on the adsorption process was estimated. The chemical stability was investigated at pH 4. Monte Carlo simulations were achieved to understand the mechanism of the adsorption process and calculate the adsorption energies. Single dye adsorption tests revealed that Zn–Fe LDH effectively takes up anionic methyl orange (MO) more than the cationic dyes methylene blue (MB) and malachite green (MG). From MO/MB/MG mixture experiments, LDH selectively adsorbed in the following order: MO > MB > MG. The adsorption capacity of a single dye solution was 230.68, 133.29, and 57.34 mg/g for MO, MB, and MG, respectively; for the ternary solution, the adsorption capacity was 217.97, 93.122, and 49.57 mg/g for MO, MB, and MG, respectively. Zn–Fe LDH was also used as a photocatalyst, giving 92.2% and 84.7% degradation at concentrations of 10 and 20 mg/L, respectively. For visible radiation, the Zn–Fe LDH showed no activity.

Inorganic nano-layered double hydroxide (LDH) materials are used in the catalytic field, and have demonstrated great applicability in the pharmacological fields. In the current study, we report Zn–Al LDH as an adsorbent for levofloxacin (levo). The physical and chemical properties of the prepared material before and after adsorption were monitored using X-ray diffraction, Fourier-transform infrared (FT-IR) spectroscopic analysis, energy dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area measurements, high-resolution transmission electron microscopy (HRTEM), and field emission scanning electron microscopy (FESEM). Density functional theory (DFT) calculations for levo and its protonated species were studied at the B3LYP/6-311G (d,p) level of theory. The removal percentage of levo was 73.5%. The adsorption isotherm was investigated using nine different models at pH 9, where the obtained correlation coefficients (R²) using the Redlich–Peterson and Toth models were 0.977. The thermodynamic parameters ΔS°, ΔG° and ΔH° were estimated and discussed in detail. Also, to support the adsorption research field, the applicability of the formed waste after the adsorption of levo onto Zn–Al LDH was investigated for medical purposes. The toxicity of levo in both normal and nanocomposite form was studied. Neither toxicological symptoms nor harmless effects were exhibited throughout the in vivo study. The oral anti-inflammatory activity, tested using 6% formalin to produce edema in the footpad, was manifested as a significant increase of 37% in the anti-inflammatory effect of the Zn–Al LDH/levo nanocomposite compared to levo in its normal form.

Nanoparticle synthesis under environmentally friendly conditions has been conducted utilizing natural resources in order to reduce the reliance on hazardous chemicals. For example, the utilization of microbial synthesis has enabled the production of nanoparticles that exhibit biocompatibility, stability, and safety. Microorganisms facilitate the growth of crystals while preventing aggregation. They serve as both reducing agents and capping agents by offering enzymes, peptides, poly(amino acids), polyhydroxyalkanoate, and polysaccharides. In this review, we present an overview of nanoparticle synthesis based on microorganisms including bacteria, fungi, algae, and actinobacteria, encompassing metals such as gold (Au), silver (Ag), platinum (Pt), palladium (Pd), copper (Cu), titanium dioxide ((TiO₂), zinc oxide (ZnO), iron oxide (Fe₂O₃), and selenium (Se). The nanoparticles typically vary in size from 1 to 100 nm and exhibit various shapes including spherical, rod-shaped, triangular, cubic, and hexagonal shapes. Additionally, this review discusses the mechanisms behind the synthesis of metal nanoparticles by microorganisms, whether they occur intracellularly or extracellularly.